1. Field of the Invention
Embodiments of the present invention relate to an electron emission display. More particularly, embodiments of the present invention relate to an electron emission display with enhanced luminance uniformity.
2. Description of the Related Art
Generally, electron emission displays refer to devices capable of displaying images by extracting and accelerating electrons from a cathode, hot or cold, toward photoluminescent layers in a vacuum environment. Electron emission displays employing cold cathodes refer to devices having cathode electrodes that, instead of employing heater (or hot cathodes), emit electrons by application of a strong electric field between cathode and gate electrodes.
A conventional electron emission display may include an electron emission unit on a first substrate, a light emission unit with photoluminescent layers on a second substrate, and a sealing member connecting the first and second substrates, so that the electron emission unit and the light emission unit may be enclosed in a vacuum envelop between the first and second substrates. The conventional electron emission display may further include a plurality of spacers between the first and second substrates to support compression force applied to the vacuum envelope. The conventional spacers may be formed of a dielectric substance, e.g., glass or ceramic, to prevent a short circuit between driving electrodes on the first substrate and an anode electrode on the second substrate.
However, some of the electrons extracted and accelerated toward the photoluminescent layers may collide with the spacers, thereby charging the spacers with a positive or negative potential with respect to the material characteristic thereof, e.g., a dielectric constant, a secondary electron emission coefficient, and so forth. The charged spacers may alter the electric field in the electron emission display, so that extracted electrons may be accelerated along modified trajectories. In other words, the electrons may not properly collide with the photoluminescent layers, thereby distorting the light emitted from the photoluminescent layers adjacent to the charged spacers. Such light distortion, e.g., color, intensity, and so forth, may trigger non-uniform luminance and reduced display quality. Accordingly, there exists a need to improve the structure of the electron emission display in order to improve luminance uniformity thereof.